Polymerization catalyst mixture of a selenium compound, a titanium salt, and a lewis acid



United States Patent ()filice 3,l2l,7% Patented Feb. 18, 1%64 PGLYM 'RiZATlGN @AEALYST MlXiURE @F A SELENE M QGMEUUND, A TITANIUM SALT, AND A LEdJlS ACE Darrell Feay, -erireley, .l'ames C. Maclrey, (Ioncord, and .loseph ll. ll-yrne, Antioch, Calih, assignors to The Dow Chemical Company, Midland, Belicia, a corporation of Delaware No Brewing. Dec. 11, 1961, Ser. No. 153,551

(ill. Zll-94.9)

This invention relates to a new catalyst composition for initiating promoting polymerization of ethylenically unsaturated monomers. it particularly concerns a new catalytically active mi. e of a selenium compound, a titanium salt, and a Lewis acid.

it is l'aown from Belgian Patents 533,362 and 538,782 to pol, rize ethylene and higher olefins With catalytically active mixtures of a compound of a transition metal from groups lV, V, and VI of the periodic arrangement of the elements, i.e., titanium, zirconium, hafnium, vanadium, niobium, tantalum, chromium, molybdenum, tungsten, thorium, and uranium, such as titanium tetrachloride, and organoalumiinim compound such as triethylaluminum. Catalysts of such kind, although perhaps catalytically active, are disadvantageous in use because the organoalumiuum compounds are hazardous in that they are generally incendiary corrosive to human flesh and are unstable in that they are easily deteriorated by moisture, air, carbon dioxide, and many other commonly encountered impurities.

It is, therefore, an object of this invention to provide an improved and novel catalyst useful in polymerization of e hylenically unsaturated monomers.

it is a further object to provide a process for producing molecular Weight solid polymers from ethylcnically unsaturated monomers.

This invention re es in the finding of a particular advantageous catalyst system that is beneficial in polymerizing a monoor poly-ethylenically unsaturated monomer, which catalyst system comprises (1) at least one selenium comoound of the formula R Se wherein each R is a monovalent hydrocarbon, alltyl, cycloallryl or aryl radical, (2) at least one titanium salt of the type TiX, and THGR); wherein X is a halide and R is as defined above; and, (3) at least one organoaluminum compound of the formula llAlX or-sin R and X above-identified.

The particular i iprovement provided by and inherent in the catalyst system of the invention comes through the role-five ease or I: tiling the components that make up the catalyst in addition to the ability to employ lower temperatures and pressures than are necessary With many of prior known catalysts. For instance, with the instant catalyst, room temperature atmospheric pressure are oft entirely satisfactory. in this respect, it is significant in the understanding of the invention to know that no combination of any two of the three components of the catalyst of the invention is active as a polymerization promoter at room t aerature or as active as the present three-compon nt ca ser ployed in the i hydrocarbc. tageously 1 to matic radical.

e the or methyl, ethyl, phenyl, benzyl, nium cor allryl, cy-cloalkyl or aros and the radicals R may lary of these radicals are pyl, hexyl, octadecyl, cyclohexyl, llrern y of some of the seleinvention are (i :iQ Se, (C 51 (C H )Se, etc. A single one or a mixture of two or more or" the 2 selenium compounds can be used in compounding the catalysts of this invention.

The titanium salt that is admixed with one ofthe selenirles described above is preferably an anhydrous salt and, as indicated, is of the type 'iiX, and Ti(OR) Preferably, TiCl is employed but other of the titanium tetrahalides are used with advantage, e.g., TiBr, and Til Of the titanium tetraalkoxides, Ti(OC H is particularly beneficial. A mixture of titanium salts may be used.

The third component in the catalyst system is a Lewis acid of the type of a mono-hydrocarbon aluminum dihalide wherein the hydrocarbon is a monovalent radical of a l to 20, r ably l to 10, carbon atom a'lryl, cycloalkyl or aryl radi l. The chlorides and bromides of the hydrocarbon alu. num dihalides, i.e., RAlCl and RAlBr are preferred in the present three-component catalysts system. Illustrative of some of these are C H Al l i-C l-l AlCl C l1 AlBr etc. A mixture of RAlX compounds may be used.

The catalyst compositions of this invention are those como 'se at least appreciable proportions of each.

which of the selenium compound, the titanium salt, and t e Lewis acid as specified.

Ordinarily, and prererably, aoout equimolar quantities of the selenium compound and the titanium salt are employed in the catalyst system with the molar quantity of the Lewis acid being about 4 times that of either the selenium compound or the titanium salt. However, the molar ratio or" selenium compound to titanium salt can conveniently range from about 1:1 to about 10:1 While the molar ratio of the Lewis acid to titanium salt conveniently ranges from about 1:1 to about 10:1.

Depending somew .t on the monomer(s) being polymerized, gencrany only a small amount of catalyst is necessary to assure the activating efiect. 0n the order of 0.1 to 10 and preferably 0.1 to 5 weight percent of catalyst based on the Weight of the polymerizing monomer is conveniently employed in the practice or" the invention.

The monomers that are beneficially polymerized With the catalysts of the invention may be broadly defined as ethylenically unsaturated monomers, including both monoand poly-ethylenically unsaturated monomers. Those monomers of the aliphatic and cyclic olefin class ng 2 to 8 carbon atoms, including both monoand cu-oletins, such as ethylene, pro T ene, butylene, and butadiene (including polymeriaable m ures thereof) and particularly l-olefins or e-oleiins, which are sci-designated because of their terminal unsaturation, are beneficially polymerized in accordance with the inver -ion. Examples of other polymerizac-le monomers that can be polymerized in accordance with the invention are the aryl olefins, particularly styrene and alkyl-substituted styrenes such as methyl styrene. Other monomers that may be polymerized by and are exemplary of the versatility of the present catalysts are vinyl chloride, acrylonitri e, methyl acrylate, etc.

The polymerizations carried out With the present catalysts are preferably performed in the presence of an anhydrous inert hydrocarbon solvent (or gas) under pres sure sufficient to maintain a liquid phase during the polymerization. In this manner, a mixed phase is usually prevalent since the catalyst is usually dispersed slurry-like throughout the solvent. Care should be taken that the solvent is free of oxygen and sulfur containing compounds which tend to deactivate the catalyst. Among the hydrocarbon solvents or diluents that can be used in the polymerization process with the instant catalysts are the alkanes such as propane, butane, pentane, isooctane, etc.; the cycloalkanes such as cyclohexane; and the aromatics such as benzene, toluene and xylene. The exact choice of the diluent will, of course, depend on the particular species of catalyst, the monomer(s) being polymerized and the particular operating conditions.

As indicated, the instant catalysts can suitably enhance polymerization at room temperature and atmospheric pressure. However, increasing the temperature or the pressure generally provides an increased rate of polymerization. Temperatures from about room temperature and below up to about 250 C. and higher can be employed. The preferred range is from about 20 to 80 C. Similarly, a rather broad range of pressure may be employed for the polymerization. For example, from atmospheric pressure and below up to any feasibly attainable pressure, e.g., 25,000 p.s.i. can be beneficially adapted. A more desirable range is from atmospheric to 100 p.s.i. or so. Again, the particular operating conditions will be in part determined by the catalyst-monomer system.

When the catalysts of the present invention are utilized, generally either the selenium compound or the titanium salt component of the catalyst is first dissolved or dispersed in a desired solvent after which the other component is added. The Lewis acid is usually, but not necessarily, added last. Preferably the first two catalyst components, in the solvent, are added to the polymerization reactor after which the monomer to be polymerized is added and then the Lewis acid is added to complete the catalyst composition and to initiate the polymerization. Other procedures are also satisfactory, such as adding the Lewis acid to the reactor containing the other two components and then pressuring the reactor with the polymerizable monomer. In any event, care should be taken to flush the reactor, and keep it free, of impurities that tend to deactivate the catalyst, as indicated, the primary ofienders being oxygenand sulfur-containing compounds, including water.

After the termination of polymerization, or when and if it is desired to stop the polymerization, the catalyst is deactivated by quenching with, for instance, alcohol or acetone, killing the reaction. The polymer is then recovered from the mixture by known means such as filtration and the catalyst is removed from the polymer by known methods.

The following examples are given to illustrate the invention wherein all parts and percentages are by weight unless otherwise specified.

, Example 1 A catalyst composition was prepared as follows. One liter of Xylene containing 2.33 grams of (C H Se was placed in a stainless steel pressure reactor after which the reactor was purged with nitrogen. Then 1.9 g. of TiCL; and 7.04 g. of (i-C H )AlOl were added to the reactor to produce a catalyst composition. The catalyst composition was used to initiate and promote the polymerization of ethylene as described below.

After purging with ethylene, the reactor was pressured to 50 p.s.i.g. with ethylene. Polymerization of the ethylene was allowed to proceed for three hours at 70 C. and then stopped by quenching with acetone. The polymerization slurry was filtered and the polymer was recovered, washed with hot acetonic-HCl solution, rinsed with acetone and dried. One-hundred-five grams of white polymer were obtained. The polymer was 57 percent crystalline as determined by X-ray diffraction technique. infrared analysis on a film flash moulded from the polymer indicated no unsaturation in'the polymer. The crystalline melting point of the polymer was 1l9.31l9.5 C. This was determined with a polarizing microscope equipped with a hot stage. The nominal molecular weight, reduced viscosity and inherent viscosity were determined from solution of the polymer in decahydronaphthalene at a concentration of 0.02 g. polymer/100 ml. at 135 C. These were: nominal M.W. 26,000; reduced viscosity 1.00; inherent viscosity 0.99.

In contrast, when the foregoing was repeated excepting to eliminate the (C T-I5) 5c, only 19 grams of polyethylene were made in four hours. This poymer was 62 percent crystalline, had a melting point of 118-12l C., a nominal M.W. of 37,000, a reduced viscosity of 1.25 and an inherent viscosity of 1.235 (0.02 g. polymer/ ml. decahydronaphthalene at C.).

Example 2 One millimole of (C H Se was dissolved in 10 ml. of toluene under nitrogen. One millimole of Ti(OC H was added to this solution and an orange solution plus a red-brown liquid second phase formed. This system was added to a glass reactor containing 90 ml. of n-heptane and 4 millimoles of (C H )AlCl to provide a catalytically active system. The reactor was purged with ethylene and filled with ethylene to atmospheric pressure and room temperature. After 24 hours, methanol was added to the polymerization slurry to stop the reaction and the slurry was filtered. The polymer was treated with dilute aqueous HCl, rinsed with acetone and dried. About 1.2 grams of dry white polyethylene were recovered which was insoluble in decahydronaphthalene at 135 C. indicating a nominal molecular weight in excess of 750,000.

When, for purposes of contrast, the procedure of Example 2 was repeated excepting to eliminate the selenide and using one millimole of TiCl and 4 millimoles of (C H )AlCl only 0.3 gram of polymer was recovered after 24 hours of polymerization.

What is claimed is:

1. A catalyst composition consisting essentially of (1) at least one selenium compound of the formula R Se wherein each R is a l to 20 carbon atom monovalent hydrocarbon radical selected from the group consisting of alkyl, cycloalkyl and aryl radicals; (2) at least one titanium salt selected from those having the formulae TiX and Ti(OR) wherein X is a halide and each R is as above-identified; and (3) a compound of the formula RAlX wherein R and X are as above-identified.

2. A catalyst composition consisting essentially of diphenyl selenide, titanium tetrachloride and isobutyl aluminum dichloride.

3. A catalyst composition consisting essentially of diphenyl selenide, titanium tetrabutoxide, and ethyl aluminum dichloride.

4. A catalyst composition consisting essentially of (1) from about 10 to 30 mole percent of a selenium compound of the formula R Se wherein each R is a l to 20 carbon atom monovalent hydrocarbon radical selected from the group consisting of alkyl, cycloalkyl and aryl radicals; (2) from about 10 to 30 mole percent of a titanium salt selected from those having the formulae TiX and Ti(OR) wherein X is a halide and R is as above-identified; and, (3) from about 80 to 40 mole percent of a compound of the formula RAlX wherein R and X are as above-identified.

5. A catalyst composition consisting essentially of from about 10 to 30 mole percent diphenyl selenide, from about 10 to 30 mole percent titanium tetrachloride, and from about 80 to 40 mole percent isobutyl aluminum dichloride.

6. A catalyst composition consisting essentially of from about 10 to 30 mole percent diphenyl selenide,

from about 10 to 30 mole percent titanium tetrabutoxide, and from about 80* to 40 mole percent ethyl aluminum dichloride.

7. A method for polymerizing an ethylenically unsaturated monomer by contacting said monomer with a catalyst consisting essentially of (1) a selenium compound of the formula R Se wherein each R and is a 1 to 20 carbon atom monovalent hydrocarbon radical selected from the group consisting of alkyl, cycloalkyl and aryl radicals; (2) a titanium salt selected from those having the formulae TlX4 and Ti(OR) wherein X is a halide and each R is as above-identified; and, (3) a compound of the formula RAlX wherein R and X are as above-identified.

8. The method of claim 7, wherein said catalyst conis an a-ethylenically unsaturated monomer containing from 2 to 8 carbon atoms.

References Cited in the file of this patent FOREIGN PATENTS Belgium June 29, 1956 

4. A CATALYST COMPOSITION CONSISTING ESSENTIALLY OF (1) FROM ABOUT 10 TO 30 MOLE PERCENT OF A SLENIUM COMPOUND OF THE FORMULA R2SE WHEREIN EACH R IS A 1 TO 20 CARBON ATOM MONOVALENT HYDROCARBON RADICAL SELECTED FROM THE GROUP CONSISTING OF ALKYL, CYCLOAKLYL AND ARYL RADICALS; (2) FROM ABOUT 10 TO 30 MOLE PERCENT OF A TITANIUM SALT SELECTED FROM THOSE HAVING THE FORMULAE TIX4 AND RI(OR)4 WHEREIN X IS A HALIDE AND R IS AS ABOVE-IDENTIFIED; AND, (3) FROM ABOUT 80 TO 40 MOLE PERCENT OF A COMPOUND OF THE FORMULA RAIX2 WHEREIN R AND X ARE AS ABOVE-IDENTIFIED. 